Protected metallic electrode



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Patented Sept. 7, 1926. 1,598,683

UNITED, STATES PATENT OFFICE.

GEORGE W. HEISE, OF BAYSIDE, NEW YORK, ASSIGNOR TO NATIONAL CARBON GOM- PANY, ENG, A CORPORATION OF NEW YORK.

PROTECTED METALLIC ELECTRODE.

Application filed May 19, 1924. Serial No. 714,454.

This invention relates to improvements in trated in the accompanying drawing, in protective coatings for those surfaces of me which 6|! tallic electrodes Which are not required to -Fig.'1is a vertical section througha cell be exposed to the electrolyte. The invention having the novel protected electrodes; and

is particularly applicable in cells of the Fig. 2 is a sideelevation of oneof'the metal-caustic alkali-depolarizing oxid type. electrodes, the coating being partly broken Reference will therefore be made primarily away. to this use, but it will be understood that the In the drawing, reference numeral 1 deinvention may be advantageously applied in notes a perforated container for depolarth ti izer suspended by rod 2 from the jar cover Caustic alkali cells ordinarily have a 3 and immersed in caustic electrolyte 4:. cathode comprising copper oxid or other Zinc plates 5 are secured in spaced relation depolarizing body, and an anode consisting to the container in any suitable manner, as of amalgamated zinc plates suspended in by being threaded upon a bolt 6 which passes spaced relation on one or more sides of the through the container 1. The zinc plates cathode. Useful electrolytic action takes are treated on the sides remote from the copplace chiefly between the cathode and the per oxid electrode to roduce a surface 7 surfaces of the zinc opposed to it. The readapted to retain a .coatlng 8 applied to it. maining zinc surfaces are subject to waste- I have obtained excellent results by treatful corrosion by local action, concentration mg the zinc surface first with nitric acid, effects, and other causes. The amount of then with a solution of an alkaline sulfid. zinc consumed in this manner may be a con- It is probable that the desirable character of siderable proportion of the total amount the treated surface is due to the formation used in the cell, particularly in service ini of mercury sulfids. Similar results may be volving low current drain. secured by using other reagents. For ex- It has been proposed to fuse an enameled ample, a solution of an alkali metal bichroiron backing to the zinc plates to prevent mate, strongly acidified with nitric acid, is 30 this waste of the zinc. The simpler expesuitable. Best results are obtained when the ,dients of coating the zinc with a paint or compound formed on the zinc surface is inplastic have heretofore been found to be 'imsoluble in the caustic alkali electrolyte. practical, for after a short immersion in the When this is the case no harm will result caustic electrolyte portions of the coating from access of the electrolyte through any become detached, perforations or pores which may be present I have discovered that the failure of such in the material applied to the zinc. The

86 coatings is due to the fact that the amaltreated surface of the zinc should not be gamated surface of the zinc does not provide exposed to any considerable extent, howa proper foundation for them. Coating maever, as the insoluble coating is not imper- 90 terials will adhere to zinc containing no vious and objectionable local action would. mercury. Unamalgamated zinc, however, is be set up.

4 rarely used in present battery practice, as The treating reagents may be a plied to the advantages of the amalgamated metal the zinc in any suitable way, as by brushing, are well rocognized. spraying, or the like.

The present invention provides a method he coating may advantageously be pitch of treating the zinc-mercury surface to enof high melting point, rubber cement, or able it to retain the coating. This method equivalent material. The essential characin general comprises chemical action upon teristics of the coatin are substantial inthe amalgamated zinc, producing a tarsolubility in caustic al ali and adhesion to nished, etched, or roughened surface.- Merthe zinc event at the relativel high tempercury appears to be substantially excluded atures which may be reache on dissolving from the treated surface and the coating adsolid caustic in water to form the electrolyte. heres tenaciously to it under service con- Low porosity is desirable. Any material ditions. having these properties will in general serve One embodiment of the invention is illusas the coating.

As compared with the coated electrodes of the prior art, those prepared by the method described herein are very efficient and inexpensive. Cells including them have excellent service characteristics."

The coating may be prepared by suitable electro-chemical processes. The expression chemical treatment and the, like, as used in the appended claims, are to be, construed to include such processes.

I claim 1. An amalgamated metal electrode having a portion roughened by chemical treat:

ment to provide a surface adapted to retain a coating. 2. An amalgamated zinc electrode having a portion superficially converted into sulfidi to provide a surface adapted to retainaf coating. f

3. An amalgamated zinc electrode having.

a surface chemically treated to prevent sub- ;tantial access of the mercury to said surace.

4. An amalgamated metal electrode having a portion chemically treated to provide a roughened surface, and a coating substantially impervious to electrolyte adherent to said surface.

5. An amalgamated zinc electrode adapted for immersion in caustic alkali electrolyte and having a portion not required for electrolytic action chemically treated to provide treating such portion to adapt it to retain a coating.

1 8'. The invention according to claim 7 1n which a superficial layer of sulfid is formed on thesaid'portion of the electrode.

9. In the manufacture of amalgamated electrodes adapted to be submerged in electrolyte and having a portion not required for electrolytic action, the method which comprises the chemical treatment of such portion to adapt it to retain a coating, and

the application of a coating thereto.

In testimony whereof, I aflix my signature.

GEORGE W. HEISE. 

